The present invention relates to improvements in rollers for use in conveying equipment, particularly of the type adapted to convey manufactured parts through a series of manufacturing stages.
Commonly conveying equipment of this type is often used to convey parts into and out of ovens where paint or the like might be dried or cured. Thus the conveying equipment must also be capable of withstanding the environmental conditions through which such parts are moved. In one configuration, rollers of the aforementioned kind consist of a metal wheel adapted to rotate and roll on a suitable guide track with a hanger element depending therefrom which carries the part to be transported. Commonly two such wheels might be located oppositely disposed with their respective hangers commonly joined and carrying the part to be transported. There are numerous other forms of similar conveyors where there is some form of wheel assembly or combination arranged in use to roll in, on, over or around a metal guide track of a desired formation. For example there are known arrangements comprising pairs of wheels journaled on a support structure with adjacent support structures interconnected by universal pivoting joints. The pairs of wheels may in some situations be arranged such that adjacent pairs have their axes of rotation generally at right angles to one another. These assemblies are often used when lighter loads are to be carried and perhaps tighter curves in the desired track are required. In such arrangements heavier loads can be accommodated by adding wheel pairs to the assembly. Commonly conveying arrangements as aforesaid, whatever, the combination or configuration, have traditionally used metal wheels with some form of bearing that required lubrication. The lubrication normally being supplied periodically by application of a grease gun to a grease nipple provided for the purpose. When such roller wheels pass into and out of ovens operating at temperatures often in excess of 400.degree. F., there is considerable strain placed on the lubricating performance of the grease. In addition, in some conveying systems, the supporting wheel combinations may be required to travel through refrigeration areas or the like where very cold temperatures can be experienced which provide a further factor affecting wheel and lubricant performance. As a result very expensive greases must be used. Despite this, even the greases available for use in hot temperature zones have temperature capabilities just above the usual oven operating temperatures and can fail in unusual conditions, i.e. being stalled in the oven zone for a longer than usual time. Of course there are also situations where conveyor systems operate in ambient or near ambient temperature conditions. Often one or more people can be continuously employed to supply grease to the rollers or wheels as they pass a certain point in the conveying system so that grease is used in such cases at a reasonably high rate. The operators can, however, occasionally overfill the roller wheels with grease and this can lead to seizure of the wheels. Finally, metal wheels rolling on metal guide tracks have the disadvantage of creating substantial and unwanted noise. There are, therefore, a substantial number of problems with these existing wheels.
The objective of the present invention is, therefore, to provide a wheel assembly for conveyor systems of the aforementioned kind which will avoid the need of lubrication such as grease and thereby overcome or substantially minimise some if not all of the foregoing difficulties with presently used metal wheel systems.